Pump or stator or map or what?

[Quart]

Good day,
question for my Busa - model 1999/2000 (350kph 16bit cpu external fuel pump). Owning it from 2016 (33.200km) to now (96.000km)
Bike has steel pipes (dekat) from 2:1X:2, PC3 usb.
The bike runs fine but shows some problems on the erogation.

History below:

All started at 90.000kms last year or so.
- First thing comes from travelling with minimum gas (example in the traffic with <10% gas throttle and below 3500rpms): while keeping the gas at a fixed % you can feel the engine "draws back" every here and there also hicc-upping.
- Second comes when you are travelling with less than 50% fuel tank (averagely 2 gallons left or less). The bike initially under heavy acceleration and later even in low pace stalls, draws back like not enought fuel. If you close the Gas Throttle minimum looks fine, open it again and partially, bike dies. Restarting with from 0 (fuel pump relais triggering) solves it.
- Third, sometimes opening as from 2-3000 rpms shows an "empty" moment when engine goes blank (for like 1/8 of second) and then ramps up.
- Fourth, milleage was horrible (10/13km per liter even at low paces)

1) What have been done @Doc mech:
- Engine head redone at 91.000kms since valve oil seals were burnt and leaked oil. Compression at cold it's 10.5, the engine head gasket was still perfect but there was junk in the coolant circuits. Everything back anew.
- Changed fuel pump filter and cleaned it
- Piston rings
- Valve stuff and chain
- Sync'd TBs

2) Bike was fine but still was dying suddently.
- Opened it and found swapped fuel hoses, setted them in order, the hoses were collapsing under heat and fuel choking the pump.
3) Improved but not enought
- Cleaned the fuel press reg screen filter (Doc Mech didn't know and it was soaked)
4) Better and worked for a while (millage ok and less stuttering) but it ate spark plugs NGK CR9EIA-9 within 4000kms.
- Noticed there was alot of struggle on fixed gas like the engine was out of sync
- Plugs were white-greyish
5) Decided to check exhausts pipes since mufflers had dbkillers completely black (bad combustion?). Discovered that dbkillers were different (one shorter than other). Ran without them and stuttering etc was much less, not unsolved but that flashed out a problem: they made TBs work unevenly.
- Ordered 2 DBkillers with better output and long the very same
- Sync'd again the TBs, fourth cylinder was skyrocketting to the moon.
- Setted TPSensor: it was out again.
- Changed plugs to standard CR9E
- Cleared BMC air filter
- Checked the Fuel Press Reg
- Increased PC3 fuel to 6-8%
6) With this we come to yesterday. After the whole went to run with 2 gallons of fuel or so. Engine felt very steady, well ramping up.
- Still while accelerating with 6 liters (1 and 1/2 gallons) or so felt the engine starving fuel.
- Slowed down at 40mph or so, slightly accelerated, it died.
- Off/On again and no problems.

This is after I sync'd and setted the TPS

7) So we have a problem and I'm not sure where to bash my head.
Excluded spark plug pipes and injectors, would run at 2-3 cylinders but not die 100% suddently
Excluded burnt clutch, could act hectic but would not die.
Excluded battery issues, I can restart as much I want, engine starter has always the 100% power
Checked tank breathing outs, they both work.
Fuel Pump hoses seems fine.

The problem seems correlated to the fuel pump: sometimes but not always seems to stop working. Only when tank is half empty or less.
Still can run around by restarting the pump and re-pressurizing the fuel rail.
Some busa bros suggested to check the stator, could be that failing hard but this would lead to fuel problems at all tank fillings.

I'm in doubt between the fuel pump starting to die or the fuel pressure regulator that stopped working or what.
What could happen if i choked the fuel pressure regulator by blocking the fuel passage 100% with a sheet of metal inbetween?
Would I have the pump keeping max pressure on rail at all times?

Any suggestion?
Thanks and good riding =)

 

[sixpack577]

If you still have the factory external pump, they are know to vapor lock in some circumstances.
Upgrading to the later in-tank pump is a good idea.
If the pump and filter are original, it is also common for them to fail with age.
Also
You said 'Decat pipe' above.
Just an fyi,
The gen1 didn't have a catalytic converter.
You can also upgrade to the 02-07 ecu with a few other parts as well.

 

[Quart]

If you still have the factory external pump, they are know to vapor lock in some circumstances.
Upgrading to the later in-tank pump is a good idea.
If the pump and filter are original, it is also common for them to fail with age.
Also
You said 'Decat pipe' above.
Just an fyi,
The gen1 didn't have a catalytic converter.
You can also upgrade to the 02-07 ecu with a few other parts as well.

Fuel Filter was changed, fuel pump cleaned (along with pressure reg screen) and this improved things alot but the problems still remains.
Vapor lock ain't an issue, this happens even nighttime with colder temperatures; happened with twisted hoses (but fixed them).
Dekat yes, since gen1 had the pipes with kats inside (two, at least in europe). Checked myself and certain at 110%.

 

[Quart]

Doing some tests, ramping up and descending a mountain (Cima Grappa) with passenger, *seems* it ran better with front light off and PC3 at +6% gas
Did 10km/liter which is awful hence there is a big issue and on flat surface still hicc-upped.

With light off seemed to run better but not always.
I'm doubtful regarding power issues (stator, rectifier) or EAP sensor (the one on the frame) or the fuel pump struggling. Maybe requires more current (Amperes) than provided, still the battery stands great (I can keep prompting the starting engine without losing an inch).. maybe it's just jammed with junk or consumed.

Bah. Will make some checks on current absorbtion and generation (testing current through the lines).
Will check EAP voltage outputs on the line. Even the IAP, you never know.

Question: if I was to exchange the (external caged) fuel pump with a replacement, what pump Could I buy "plug and play"?

 

[sixpack577]

@chrisjp has a gen1 fuel pump thread here somewhere, with a good an inexpensive fix.

 

[Quart]

@chrisjp has a gen1 fuel pump thread here somewhere, with a good an inexpensive fix.

checked his threads, couldnt find the right one :| let's hope he'll come in aid. I've also seen the BB thread about putting a secondary low-pressure pump in line, but if main pump struggles to keep the pace, will die sooner or later regardless the secondary pump :|

 

[Quart]

Updates: changed fuel pump with a Quantum FP that fits perfectly. I can smell better exhaust output (less unburnt gasoline), but still some hiccups at low speeds (less than 3000 rpms with <10% gas open).

Had an idea: when redoing the throttle body sync i noticed that with or without airbox and filter differences were really slight (AB and filter does limit air flow, hence minimum ought to increase/decrease noticeably with and without airbox/filter).
Swapped out the BMC air filter and threw in an old hi-flow filter. Result: much more stable gas at low revs while driving in the traffic.

Problem: still high fuel milleage (12~ kms per liter, around 30mpg). Spark plugs are OK, not burn or fooled.
Since FP does its work, I'm wondering if it's a matter either of leakage from injectors or Fuel pressure regulator.
Will do more tests when possible, I'm aiming to put an extra-long 2mm hose from the reg to the throttle bodies and check if I can sniff fuel in it (current one being original it's too short and fuel just vaporizes).

Replacing that regulator it's a nightmare, it's sold with the full OEM Pump (500 dollars or so) and aftermarket it's not sold. I'm looking for the CBR 954 reg, looks similar except the return

gauge, but if I can adapt it may work.

 

[Quart]

Out of ideas brought it to a prof.
Dunno if they did something inbetween, these are the sheets atm. Today will call forth for updates on what's going.

 

[Quart]

So, got it back from the workshop, they mapped it, changed the EAPs (external air pressure sensor).
Seems to work better, still same fuellage and similar struggle at low revs while driving in the traffic under 10% gas throttle. Less than before, so the EAPs was a culprit but not the only one.

So restarted myself checks and wondered: what the heck says to the CPU that I'm going in a certain way? the TPs.
So went to check the TPs and discovered that while the manual says it ought to be 1300/4500 ohm CT/WOT on mine it's 1200~/4200 ohm.
So it's less than it should. Voltage on it it's ok (don't remember if 4,5 or 5V but it's ok). The resistance scales perfectly from 1200 to 4200 without struggles or jumps. The TPs was setted to C00- by me with the CPU shortway system.

So Instead of leaving it to C00- I decided to jack it off and moved it again until 1400~ohm minimum and 4300~ maximum. Why?
My reasoning is this: let's state that the TPs potentiometer it's old, jacked and so on. Either I keep it this way or replace it (200€!!!).
But let's think it more deeply: my electrical supply it's better than original.

Noticed it wasn't uppin the voltage rightly. Discovered that the connector beneath the tank from the alternator to the rectifier was blown fuse. 1 cable was deattached, others were burning off. Cleared everything and replaced the connector and faston with new ones. Back to 14,5 stable voltage

So let's say that the potentiometer it's expended, not totally, but absorbs more current cause some resistance has gone to heaven.
More absorbed current = less resistance anyway, especially where the rectifier it's more powerful than the OEM and provides more current to the whole circuit!

So if V=R*I then R=V/I and if Voltage is stable at 4,5V from the CPU, then current ought not since it depends by the whole electrical system.
And if the elect. system allows more current to be absorbed so will the potentiometer, decreasing the native resistance (examples R = 4,5V/0,1A = 45ohm, but 4,5/0,2 = 90ohm).

If throttle sends a voltage to the CPU based on the resistance, if resistance changes the signal due to the lower asset so the CPU will think to a lower Open throttle and while you are cruising at 5/10~% throttle the CPU ought to think it at 1-3~% throttle. Unfortunatly it's not alone, there is also the IAPs along and the EAPs doing their job, and especially IAPs says "hey bro, TP says 1-3% but I dare to say 5/10%!" Since IAPs reads the depression caused by the opening throttle in the throttle bodies.
Hence the CPU goes confused kinda "WTF one says 1-3 other says 5-10!" and shoots fuellage at random causing the struggle.

Noice story indeed, will have to test this setting if was the culprit.
Unfortunatly today gotta go for some days in France hence will try it better next week.

Ps. will soon swap engine oil (not many kms but 1 year or so) and spark plugs (not many kms but will replace with CR9EK).

 

[Quart]

Update, after testing the TPS moved on higher resistances, low revs seems to struggle way less on/off but fuel consumption still high (11-12kms/lt). Hence that's not the issue. The fact that struggle less on light gas it's because the engine *feels* the gas more opened than it is really and adjust better the cut off. Will check in different ways (will retest the IAT sensor).

On second thought, my battery and rectifier do a great job, like 12,9v battery off after some hours, 14,5v rectifier engine on with lights on at minimum/max. Wondering if the fuel pump gets too much voltage (fuel pump it's a Quantum FP replacement).

 

[Quart]

Today I unmounted the TP sensor and checked for flaws.
No flaws really, if i turn it from zero to max it goes from 900 to 4900 ohm, hence it does its job. I guess that the fact it does not reach 4500 lies in the TBodies themselves, the butterflies does stop too early (but they are done in this way).

Anyway inverted it, it was at 1400~/4300 before, now i reverted it to 1100/4100 ohm setup. Let's see how it goes

 

[GIXERHP]

If you still have the factory external pump, they are know to vapor lock in some circumstances.
Upgrading to the later in-tank pump is a good idea.
If the pump and filter are original, it is also common for them to fail with age.
Also
You said 'Decat pipe' above.
Just an fyi,
The gen1 didn't have a catalytic converter.
You can also upgrade to the 02-07 ecu with a few other parts as well.

As well as the original fuel lines collapse over time

 

[Quart]

That was fixed by myself, applied 90° brass joints and reinforced hoses to avoid collapses and chokes.

Anyway updates. Mounted old filter, no substantial difference, mounted then 4-2-1 exhaust.

Less power, in the way that with 4-2-X1-2 appeared like a 2T engine. Anyway did a 240km or so, managed nearly 16km/lt with girl along with me and across mountains so I guess we found the culprit.

But why? In my humble imagination of fantasy (not a mechanic or engeneer or what, just basic electrician) we have the cross valve timing where both in and out are open and inlet allows to wash the inside of the cylinder to clean the exhaust gasses.

With 2-1X-2 with 61mm per pipe i guess the depression on the out was so great but so great that the air traveling in-->out was way too much, hence the bike squirting fuel for nothing. With 4-2-1 we get way less pipe size (still 62mm but just 1) so higher counterpression hence less air to wash the exhaust chamber.

Solution ought to be setup the cams with less cross-valve time, like retarding the opening of the IN camshaft by a teeth or so in order to mantain the double exhaust.

Next on the future: will put back the BMC air filter and probably disable the airbox flapper. This could slow down the air speed inside the cylinder hence reducing the depression inside the TBs (venturi effect) and low speeds.

Suggestions?

 

[Kiwi Rider]

Wow… I think you’re analysis is way more advanced than anyone here can do.
Keep going, you’re about to redesign the space shuttle lol.
Seriously though, I’ve learned a bit more than I’ve known already by reading this thread.
It’s all a process of elimination, you’ve covered so many points it’s getting tuned little by little!
I also have an early Busa that has the external fuel pump… mine runs really well with an Akra full exhaust system, a K&N air filter, a PC3 with a generic Akra map installed courtesy of the Power Commander website, and the PC3 tuned via the buttons on top of the box set to lean it off a lot, in the low end and the mid range.
Mine has 147,000kms on the original engine, 200 to 210psi on the compression test on each cylinder. New cam chain, manual cam chain tensioner, stage 1 Yoshi cam grind.
Be sure to have the fuel pump insulated with the OEM “sock” installed, to insulate it from the heat of the crankcase and cylinders.
Check the fuel pressure too, must be 3 bar or 42psi and steady at that pressure when idling, under load, accelerating , whatever.
Keep going, you’ll get there, your perseverance is impressive!

 

[Hayabusa Wannabe]

Is the tank venting working? Is there vacuum building up in the tank holding back fuel? In this case, if it died, then the tank was opened, "whoosh" an inrush of air would occur.

 

[Quart]

Ye, tank is venting, breath hoses are clean and passing. The issue is genenerally from the hoses getting squeezed by the depression cause by the pump plus the warm air coming from engine.

Anyway mounted the BMC Air Filter, power goes way better, milleage goes slightly down but not too much.

So I did this round (girl carriaged), plus some extra kms here and there, crossed the highway on return with rain storm and wind counterwise (consider that cars were going between 25 to 50 mph, anyway I could still speed safely at 62-65mph regardless rain and wind). Total around 310kms (there is also work travel). 20,5 liters (5,4 gallons) for 310kms (193miles) and that's 15,1 kms per liter (aka 36mpg around).

Now, stated that i hit the right spot I'll reach for 100.000 round kms (atm 99.500) and then redo filters oils and spark plugs (they got around 6-7000km). Will try out the CR9EK over the standard CR9E spark plugs.
I'll try to remove the sealers from the air box-to-frame that i've actually, my guess is that the airbox HAS to draw the air around the engine in order to limit the air speed at low rpms, hence the fuel efficency. I'll install a trigger in order to enable/disable the vacuum of the airbox Flapper valve.
I'm wondering about installing a simple clip over the flapper valve so it will remain slightly more open while completely closed.

For the next future: Transmission kit, atm I'm using 17/40. Wondering what about a 18/43 like Hayabusa 2008, this with "standard chain" with 112 rounds, maybe another round or two will be needed to not shrink too much the distance of the rear wheel. 18/43 increases the diameters of both front and rear sprokets, hence closing the ratio at par chain.

 

[sixpack577]

The Small Airbox Mod is to remove the flapper. That can improve things even without a tune.
The Large Airbox Mod removes more of the box around the flapper, and does need a tune.
Both improve the engine's efficiancy when properly tuned.

 

[Quart]

Tried the airbox mod but i guess I did it bad (have still in in my box somewhere). It ate so much air that at minimum needed two rounds of minimum idle for extra fuel.
Had not much time to run here and there, atm just at 102.400kms or so. Said this finally did some works:
- first changed the cables that brings the current from stator to rectifier. Old ones were burned, set an external 10A triple insulated cable (sounded absurd to have high hertz currents spinning close to the electronic cables), insulated jacks and so on.
- second I finally managed to get the fitting male&female jacks for the Airbox Air Sensor (IAT). Interesting is that I added a potentiometer and a switch.

Regarding this my Idea on test is like... but before a little step back: above wrote something regarding deleting the airbox insulators I did ages ago. Bad choiche, during traffic in the mountains on slow U-turns engine overheated a little (not at flash), issue was that it got to a negative feedback loop. Consider this: the IAT reads air inside the airbox but if you are running slow in the hot (air, sunny day) and you have airbox as original not insulated, engine will draw slowly air from outside the airbox hoses above the engine. So IAT reads hot air, CPU says "hot air = less oxygen = less fuel" and leans the mixture. So engine warms more, seding hotter air to IAT who says it to CPU who leans more...

Said this back at home reinsulated everything and GG but it game me an Idea. Consider i cut out the PC3 since remap but still wanted to hang around this so checked for jacks male&female that fitted the air temp sensor and the female original jack.
Next added a circuit where from the female: grounds doubles, one goes to the sensor (swapped with a new Febi-Bilsten for cars and 18€) and one goes to a potentiometer (0-3,3kohm).
Next +5V from CPU goes to a switch that either plugs to the sensor or to the potentiometer (or to nothing).

So now I can start the engine in "automatic" and later switch to "manual" where I decide the "temperature" by rolling the Potentiometer. From the workshop manual

you see that tot Resistance tot temperature. At 10°C it's like 3Kohm.
So from this I can tell the CPU to lean by reducing the resistance. Guess that you cannot run it way too lean so from 1,5 to 1kOhm is the waytogo.

So far no changes tho, I've still the CR9EK spark plugs on, wonder if they are working good. Time will tell, we will see.